In data storage systems, data is recorded on a storage media, typically in data tracks. For example, in disc drive data storage systems, data is written in circular concentric data tracks on the surface(s) of one or more data storage discs. In magnetic disc drive data storage systems, advancement in material science has allowed magnetic data to be written on the media at greater track pitch per inch (TPI) densities than had previously been possible. One factor which makes recording at higher TPI densities possible is a reduction of the transducer's geometry. Synthetic anti-ferromagnetic (SAF) transducers have been used in magnetic storage systems to achieve higher TPI (for example, 130 TPI). The properties of SAF transducers have proven to provide good thermal performance, amplitude response, amplitude asymmetry sigma, and component stability as compared to other transducer types.
However, one problem which can occur with SAF transducers is that they frequently exhibit polarity flip behavior. A polarity flip, or polarity flip behavior, is where a read back signal from a data head inverts from its original or previous polarity. Inversion of the read back signal will result in data errors. Transducers such as SAF transducers are sensitive to polarity flips, and particularly to flips to negative polarity. Transducers will also give a reverse polarity reading of the read back signal if the transducer wire is soldered in a reverse orientation. In order to implement proper decoding, the read/write channel requires that the signal polarity state be known and correct. Therefore, there is a need for methods and apparatus which can accurately detect head polarity and head polarity flips automatically.
Embodiments of the present invention provide solutions to these and/or other problems, and offer other advantages over the prior art.